1. Field of the Invention
The present invention relates to a method for manufacturing a liquid ejection head.
2. Description of the Related Art
A thermal type liquid ejection device causes film-boiling of liquid, such as ink, using thermal energy generated by energizing energy generating elements, and ejects the liquid from an ejection port utilizing pressure generated by the film-boiling to perform recording operation.
Such energy generating elements are covered with an insulating layer in order to secure the insulation between the elements and ink. Furthermore, a protective layer containing metal materials, such as tantalum and iridium, is provided in order to protect the energy generating elements from cavitation impact associated with disappearance of bubbles or chemical action caused by liquid. However, when the insulating layer has a hole (pinhole), electricity flows between the energy generating elements and the protective layer, which raises concern that desired heat generation properties are not obtained in recording operation and also the protective layer causes an electrochemical reaction, and thus deteriorates to reduce the durability or materials of the protective layer are eluted. Therefore, it is required to inspect the state of the protective layer in a manufacturing stage of a substrate for liquid ejection head to confirm that the energy generating elements and the protective layer are not conductive to each other.
Japanese Patent Laid-Open No. 2004-50646 discloses a method for inspecting insulation using an inspection terminal connected to a protective layer that is provided in the shape of a belt in such a manner as to protect a plurality of energy generating elements in common and an inspection terminal connected to the plurality of energy generating elements in common. According to the method, the plurality of energy generating elements can be collectively inspected for the insulation by an insulating layer.
However, in the configuration disclosed in Japanese Patent Laid-Open No. 2004-50646, the plurality of energy generating elements are covered with the protective layer which is continuous in the shape of a belt. Therefore, when the energy generating elements and the protective layer enter a conductive state even at one portion during recording operation, a current flows to the protective layer covering the other energy generating elements. As a result, the entire protective layer deteriorates, which raises a possibility that poor ejection occurs in all the energy generating elements, so that recording operation cannot be continued.
In order to prevent the problem such that poor ejection occurs in all the energy generating elements in a chain reaction manner, it is considered to provide protective layers in such a manner as to be electrically isolated and independent from each other for each energy generating element. However, in such a case, an inspection of confirming the insulation between the protective layers and the energy generating elements need to be performed for each energy generating element, which requires a huge number of inspection terminals and huge time for the inspection. Thus, the efficiency is not good.